Organic fluorine compounds and process for making same



United States Patent 3,102,915 ORGANIC FLUORIWE COMPOUNDS AND PROCESS FOR'MAKING SAME Murray Hauptschein, Montgomery County, and Milton Braid, Philadelphia County, Pa., assignors to, Pennsalt Chemicals Corporation, Philadelphia, Pin, a corporation of Pennsylvania N0 Drawing. Original application July 23, 1957, Ser. 'No. 673,578, now Patent No. 3,008,966, dated Nov. '14, 1961. Divided and this application May 17, 1961, Ser. No. 115,849

Claims. ((11.250-608) This invention relates to a novel process for the preparation of organic compounds containing fluorine and to new and useful organic compounds containing both fluorine and sulfur. This application is a division of our copending application Serial No. 673,578, filed July 23, 1957.

The value of fluorine in organic compounds has long been recognized. In general, the presence of fluorine gives much greater chemical and thermal stability than would be present in compounds not containing fluorine, and such properties are highly desirable in many industrial applications.

The desirability of introducing sulfur into fluorine-containing organic compounds has also been known. Sulfurcontaining fluoroorganic compounds have many uses such as in high pressure lubricants, cutting oils, insecticides, and heat transfer fluids. In addition, the sulfur group is valuable in providing compounds which serve as intermediates in the production of other valuable fluoro'orgauic compounds.

It has now been found that fluorine-containing organic iodides may be reacted with mercuric sulfide to provide a series of polysulfides or to provide novel heterocyclic compounds depending upon the iodide used and the reaction conditions. These novel heterocyclic compounds are especially useful as heat transfer media and high temperature coolants.

In accordance with this invention, there is provided a method for making organic fluorine compounds containing sulfur, which comprises reacting an iodide having the formula where R is a member of the class consisting of perfluoroalkyl groups having from 1-30 carbons and perfluorochloroalkyl groups having from 1-30 carbons and having the carbon atom a to the C carbon atom in the formula free from chlorine atoms directly attached thereto, and Y is a member of the class consisting of fluorine, chlorine, perfluoroalkyl groups having from 16 carbon atoms and perfluorochloroalkyl groups having from 1-6 carbon atoms, and having the carbon atom on to the C carbon atom in the formula free from chlorine atoms directly attached thereto, with mercuric sulfide.

It will be understood that the invention involves reactants in which the R and Y substituents are the same as well as those in which they are different.

As used in this application, a perfluoroalky group means a substituted 'alkyl group containing only fluorine and carbon.

A perfluorochloroalkyl group is a substituted alkyl group containing only fluorine, chlorine and carbon, and in which the atomic ratio of fluorine to chloride is greater than one.

The reaction varies somewhat depending upon whether the iodide used is a primary or secondary iodide. When primary iodides are used, the reaction products are dior polysulfides. On the otherhand, when secondary iodides are used, the products may be dior polysulfides or they 3 ,102,91 5' Patented Sept. 3, 1 963 may be novel heterocyclic compounds depending upon the reaction conditions.

When primary iodides are used, thereaction involves reacting a compound having the general formula RC XFI where R is as defined above, and X is a halogen having an atomic number less than 20, and provides compounds having the formula (RCFX) S where R and X are as defined above, and n is an integer It will be understood that the reaction may involve two molecules of the same iodide, or one molecule of each of two different iodides.

The reaction may be carried out under a variety of different conditions. Preferably ultraviolet or other dorms of ionizing radiation such as x, 'y, or high energy electron are used. Heat may also be employed to initiate the reaction.

The reaction temperature is not critical; and when ultra violet irradiation is used, the reaction may be carried out at room temperature or even lower, for example, at -20. C. When. heat alone is used, without ionizing radiation, the temperature should in general be above about C. On the other hand, higher temperatures may be used and the reaction may be carried out at temperatures as high as or higher than 300 C. Pressure is also not critical, and generally may be from about atmospheric to about 10,000 p.s.i. g. Time of reaction is again not critical and may be from a matter of say ten minutes to several days. The proportions of mercuric sulfide used will depend to some extent upon the amount of sulfur it is desired to have in the final product. Generally between about one and about 20 mols of mercuric sulfide (HgS) will be present, per mol of iodide. Preferably at least 2 mols of I-lgS will be used per mol of iodide.

. In carrying out the reaction of these primary iodides with mercunic sulfide any suitable technique may be employed. Conveniently, the ingredients are simply put into a suitable container such as a glass vessel, in an inert. atmosphere, and heated to the desired temperature with stirring while being subjected to ultra violet irradiation from a suitable ultra violet source. in certain cases, panticularly when the iodide is a solid, it may be desirable to use an inert solvent. Alternatively, the reaction may be carried out by passing the reactant through a glass tube which is subjected to ultra violet irradiation.

When secondary iodides are used, the, reaction involves reacting a compound having the general formula where R is selected from the class consisting of perfiuoroalkyl groups having from 1 to about 30 carbon atoms and perfiuorochloroalkyl groups having from 1 to about 30 carbon atoms and having the carbon atom on to the C carbon atom in the formula free from chlorine atoms directly attached thereto and where R is selected from the class consisting of perfluoroalkyl groups having from 1 to about 6 carbon atoms and perfiuorochloroalkyl groups having from 1 to about 6 carbon atoms and having the carbon atom a to the C carbon atom in the formula free from chlorine atoms directly attached there'- to. R and R may be the same, or different.

Among the secondary iodides that may be used in the practice of this invention, the following may be cited as exemplary:

' It will be understood that the reaction may involve two molecules of the same iodide, or one molecule of each of two different iodides.

I At temperatures below about 200C. secondary iodides will in general enter into the same reactions as those indicated above for the primary iodides, i.e. they form di-or polysulfides of the general formula where R, R, and n are as defined above. At temperatures above about 150 C. the reaction proceeds smoothly regardless of whether or not ultra violet radiation is employed. will go at room temperature or even lower, for example, down to 20 C.

Above about 200 ,'C., the formation of certain novel heterocyclic compounds to be described more fully below is favored, although some heterocyclic formation is encountered at temperatures above about 175 C. When ultra violet or other radiation is used, some heterocyclic product may be formed as low as 100 C.

In carrying out the reaction with secondary iodides pressure is not a critical factor. In general it will be between atmospheric and about 10,000 p.s.i.g. Time of reaction is again not critical and may be from about ten minutes to several days. However, if too short a reaction time is used, a mixture of the novel heterocyclic compound and dior polysulfides may result even at temperatures over 200 C. To insure reasonable conversions to the heterocyclic compound a reaction time of at least 20 minutes should be used. The proportion of mercuric sulfide used will be generally from between about about one molto about 20 mols of mercuric sulfide per-moi of iodide. To obtain reasonable conversion to the heterocyclic compound at least two mols of HgS should be present, per mol of secondary iodide.

As in the case of primary iodides, various conventional techniques may be employed for carrying out this process. Any suitable vessel may be used such as a stainless steel or Monel autoclave or, as in the process using ultraviolet irradiation, a glass vessel may be used. The ingredients may be placed in such a vessel or passed through a tube of similar material, mixed together with or without addition of an inert solvent, and subjected to heat or irradiation until the reaction is completed.

As has been stated, if a secondary perfluoroalkyl or perfiuorochloroalkyl iodide is reacted with mercuric sulfide at temperatures in excess of 200 C., a novel heterocyolic compound is formed. In general, the other reaction conditions for the high temperature production of the 'heterocyclic compound are similar to those set forth above for the reaction of secondary iodides at tempera tures of 200 C. or less, and similar reactants may be used. However, no ultra violet irradiation is required. The reaction may be carried out at temperatures of 300 C. or higher and a temperature range of from say 200 C. to 400 C. is considered practicable for this reaction although it is preferred to use temperatures from 200 C. to about 300 C. The excellent thermal stability of these cyclic compounds render them valuable as heat transfer fluids and high temperature coolants.

Using ultra violet radiation the reactions 7 Identification tests indicate that the novel cyclic compounds formed from the secondary iodides described above have the general formula where the R and R substituents are as defined above. It is to be understood that the above formula includes the various possible stereoisomers. The two Rs and the two Rs'may be the same or different and either or both Rs may be the same as or different from either or both R"s.

In order to determine the structure of the novel heterm cyclic compounds of this invention, the reaction of 2- iodoper-fluorohexane and mercuric sulfide was carried out at about 230 C. The reaction product was purified and analysed. The empirical formula for this product was C F S This compound represents formally loss of one IF molecule from each of two C F CFICF molecules with addition of two Satoms, i.e.

The nuclear magnetic resonance spectrum for this 'compound indicated the presence of three types of CF groups and two types of CF;.; groups, but no group was indicated. The lack of I s-os-o system of cyclic structure. From this and other evidence, it is concluded that this new compound has the structure As noted above, the formation of the heterocyclic compounds appears to involve the removal of the elements of IP from the same carbon atom of each reactant iodide. It has also been noted that at lower temperatures and for shorter reaction times the interaction of 2-iodoperfluorohexane with mercuric sulfide gave predominantly perfluoro-2hexy1 polysulfides rather than the heterocyclic compound. These facts suggest that a dior poly-sulfide formation is an intermediate step in the formation of the heterocyclic compounds. Evidence that this is actually the case, was the successful conversion of polysulfides, such as perfluoro-Z-hcxyl polysulfide, in the presence of mercuric sulfide to the corresponding heterocyclic compounds, such as C F S None of the latter was observed when the polysulfides were heated alone.

Accordingly, the invention comprises a method for making heterocyclic compounds of the above type by the thermal reaction of a secondary perfluoroalkyl or perfluorochloroalkyl polysulfide and mercuric sulfide as well as from the secondary iodides. Stated more exactly, this I which are cited as exemplary:

. aspect of the invention comprises a process in .which compounds having the general formula Where n, R and R are as defined above, are reacted .with mercuric sulfide to provide compounds having the formula be prepared as hereinabove described or they may be prepared by the method set forth in the application of Murray Hauptschein et al. Ser. No. 646,202 filed March Although details :of the mechanism have not fully been established, when a cyclic compound of the above character is prepared by the thermal reaction of secondary fiuoro-iodide and mercuric sulfide, it is believed that the reaction proceeds according to the following equations The novel heterocyclic compounds are non-corrosive and have excellent thermal stability, so that they can be used as heat transfer media, particularly in systems where iron, aluminum 101 other similarly constituted elements would present corrosion problems. They have low surface tension and can be used, for example, in automobile polishes to prevent dirt pick-up and make painted surfaces more resistant to deterioration. They also can be used as solvents, lubricants, dielectric fluids and working fluids in hydraulic systems.

The invention will be further described with reference to the following specific examples, it being understood that these examples are given for the purpose of illustration only and are not to be taken as in any way limiting the invention beyond the scope of the appended claims.

The mercuric sulfide used in the following examples was prepared by triturating small portions of mercury in a mortar with excess sulfur until completely consumed. The resulting greyish-black powder was exhaustively extracted with carbon disulfide in a Soxhlet extractor to remove unreacted sulfur. An X-ray pattern was identical to that of an authentic specimen of cubic HgS.

Example 1 violet burner, used without the Woods filter, while shaking vigorously end to end in a horizontal position. The tube is cooled in Dry Ice and opened, and volatiles are transferred in vacuo to a small still. By distillation there is recovered 1.4 g. of the reactant iodide. A liquid fraction (1.2 g), B.P. 60 at ca. 100 mm., n 1.320, spectroscopically pure perfluoropropyl disulfide, is obtained as the sole reaction product in 38% yield. (Additional product probably remains adsorbed in the solid mercury salts) Analysis.Calcd. for C F S C, 17.9; F, 66.1; S, 15.9. Found: C, 18.2; F, 66.0; S, 15.9.

Example 2 In a heavy-wall Pyrex anipoule 5.9 g. (0.02 niole) of l-iodoperfiuoropropane and 11.7 g. (0.05 mole) of black mercuric sulfide are sealed under an atmosphere of dry high-purity nitrogen. The tube is heated for about 68 hours at temperatures of 225-230". After cooling in Dry Ice, the tube is opened, and volatile products are transferred at ca. 0.1 mm. to a small Vigreux distillation unit. Distillation does not separate any pure materials. Infrared spectroscopic examination reveals the presence of Example 3 The compound CF OF OFCII is reacted with black mercuric sulfide under ultraviolet irradiation, using the general technique of Example 1. Products having the formul (CF CF CFCD S are obtained, with n being from 2 to 5.

Example 4 The procedure of Example 1 is repeated except that CF ClOF CF I is used and compounds having the formula (CF ClCF CF S with n being from 2 to 5, are ob tained.

Example 5 A mixture of 8.9 g. (0.02 mole) of 2-iodoperfiuorohexane, 11.7 g. (0.05 mole.) of black mercuric sulfide and 13 ml. of l,1,Z-tribhlorotrifiuoroethane are sealed under nitrogen in a 60 cc. Vycor No. 7910 ampoule and irradi- Example 6 The compound CF CF CFICF and mercuric sulfide are sealed and irradiated using the technique of Example 5. Products having the formula (CF CF CFOF S are obtained. 7

Example 7 Under a dry high-purity nitrogen atmosphere, 8.9 g. (0.02 mole) of 2-iodoperfiuorohexane and 11.7 g. (0.05 mole) of black mercuric sulfide are sealed in a heavywall Pyrex ampoule. The tube is heated in a molten salt bath at temperatures of 225-230 for 68.5 hours. After cooling in Dry Ice, the tube is opened, and the liquid portion'of the reaction products is distilled at -0.1 mm. into a small Vigreux still. From this portion there are finally obtained by careful distillation 1.1 g. of a liquid,

B.P. 53-59", n 1.28; 0.8 g. B.P. up to 55 at mm., 11 1.308 shown spectroscopically to contain several components (not further characterized); and 3.5 g., B.P. 142 at 1001mm, main cut, B.P. 142 at 100 mm. and 36-37 at ca. 0.1 mm., a liquid, 11 1.331. Upon stand ing, white crystals, M.P. 62, are deposited from the latter fractionfor which the infrared spectrum is virtually the same (taking into account the normal differences between liquid and solid in Nujol, mull spectra) as the 7 8 mother liquor. The conversion to the heterocyclic In order to determine the stability .ofthis compound C F S is 53%. to the action of chlorine, a small Carius tube contain- The compound is used in place of a salt bath to furnish ing 0.6 g. of the heterocyclic 'C F S and ca. 0.5 g. heat to a reaction carried out at 350? 0., without perceptichlorine is sealed in vacuo and heated for 2.75 hours at ble decomposition. 5 90-110. The tube is cooled and opened and the chlo- Example 8- rine is removed by heating the contents under reduced F ll i h procedure f Example 7 pressure. The residual material is shown by the infrared cFzclcP-(cFs) [OF2OF(CF3)]3I spectrum to be entirely the reactant C I- 8 is reacted with black mercuric sulfide at a temperature of 10 Example 12 about 235 C. for 16 hours. The product By heating a mixture of 8.9 g. (0.02 mole) of 2-iodo- CF; CFICICF(CFB)[0F3CF(CF3)12CF1CS S-(f-CFzKCFa)CFCF2]2(CF3)CFCF2C1 CF: is obtained. perliuorohexane and 11.7 g. (0.05 mole) of black mer- Example 9 ouric sulfide for 50 hours in an oil bath at 195 there i I 20 is obtained 5.8 \g. of liquid products boiling up to 50 Following the procedure of Examp 1e at ca. 0.1 mm. which are shown by their infrared spectra a '1[ 2 3)]9 to consist mainly of perfiuOro-Z-hexyl diand'polysulis reacted with black mercuric sulfide at 250 C. for ten fides containing a Small amount heterocyclic 012132482- hours. The product Example 13 i Eleven and one-half g. (0.026 mole) of Z-iodoperfluo- C3F1[CF1CF(CF3)]BCF1C-S rohexane and 14.5 g. (0.062 mole) of black mercuric CCF2[(CF3)CFCFz]3C F sulfide are heated with shaking at 230 .for 17 hours.

a The tube contents are extracted with 1,1,2-triohlorotriis obtained fluoroethane and filtered. The filtrate is distilled, and, Example 10 after removal of the solvent, there is collected 4 'g. of llquid distillate, B.P. 54-58/20 mm., m; 1.334, WhlCh The Product of Example 7, hetemcyclic 12 24 2 is is shown spectroscopically to consist of approximately Pounded into an automobile Polish having the fiollOWing equal amounts of perflu'oro-Z-hexyl polysu lfides and the formulation heterocyclic C F S Parts by weight E l 14 Carnauba wax 4 8 Ozoherite wax 2 One-half gram of mercuric sulfide and 1.7 .g. of per Hard paraifin 3.5 fluoro-2-hexyl polysulfide are sealed in a Pyrex Carius I-Ieterocyclic C F S prepared as in Example 7 40 tube and heated at 260-267 ior'one hour and at 270- above 0.5 279 for one additional hour. From this reaction there Mineral spirit 40.0 are finally obtained 1.2 g. of liquid product consisting I of 30-35% of the heterocyclic C F S (determined by 50.0 infrared spectra) and 65-70% of unconverted polysu1- fides. Some etching is observed on the tube walls, and fluoride ion is confirmed in the residual solids. In addition, elemental sulfur is present.

None of the heterocyolic 0 F 8} is detected when 1.5 g. of perfluoro-Z-hexyl polysulfide is heated in a Y a Procedure similar to that of Example =g- Pyrex Carius tube at 299-307 for 1.5 hours. (0.01 mole) of 2-iodoperfluorohexane and 3.2 g. (0.014 mole) of black mercuric sulfide are heated in a salt Applied to an enameled metal surface this material leaves 45 a hard, glossy film having excellent moisture and dust resistance. t r

' Example 11 Example 15 bath for 65 hours at a temperature of 235. From the Using the procedure of Example 14, the compound blue liquid product of this reaction there is obtained 1 r 0.4 !g. of recovered iodide and ca. 2 lg. conversion) OF2CICFV(CF3) fga gg (CF )CFCF C1 of pure C F S liquid, B.P. 4244 at ca. 0.1 mm., 55 3 2 3 3 2 "n 1333- n tanding, nearly all of the liquid crysis heated with black mercuric sulfide for one hour at 1121111268 into a White solid, M.P. Analyseslor car- The 'hetemcyclic compound omelet(GFMOFZGF(oFolzoFr-h-s SCCF2[(CF3)CFCF2lt(CFa)CFCFzGl O Fa hon, fluorine, and sulfur for the solid and the liquid are is obtained. in agreement as are the infrared spectra, except for the Example 16 slight diiferences between pure liquid and dispersed solid 65 Using the procedure of Example 14 the compound spectra noted previously and matching the infrared spectra obtained for the solid and liquid of the previous 3 7 2 a) 9 a)' 2]9 a -1 i l is heated with black mercuric sulfide rfor one-half hour at Analysis.-Ca1od. tor C F S C, 21.7; F, 68.7; S, 90 The heterocyclic compound 9.65. Found: C, 21.9; F, 69.9; S, 9.31. CFa

' Characteristic infrared absorption bands (in microns) I or the supercooled liquid :fractionare: 7.40, 8.20-8.24, C3F[CFCF(CF3)]CF C S 8.42, 8.81, 9.37, 9.68, 10.28, 10.79, 11.13, 12.77, 12.96, (')CF2[(CF)3CFCF2]6CaF7 13.42, 13.69, 13.84, 14.15, 14.5. No bands in the CF.S C-C region are. present. is obtained.

containing sulfur, which comprises reacting an iodide having (the formula RC YPl Where R is amember of the class consisting of perfiuoroalkyl groups having from 1 to about 30 carbon atoms and per-fiuorochloroalkyl groups having from 1 to about 30 carbon atoms in which the carbon atom or to the C carbon atom in the formula is free from chlorine atoms directly attached thereto, and Y is a member of the class consisting of fluorine, chlorine, perfi-uoroalkyl groups having from 1 to about 6 carbon atoms and perfluoroohloroalkyl groups having from 1 to about 6 carbon atoms in which the carbon atom a to the C carbon atom in the formula is free from chlorine atoms :directly attached thereto, with mercuric sulfide.

2. A method for making organic fluorine compounds containing sulfur, which comprises reacting a primary iodide having the formula RC XFI where R is a member of the class consisting of perfluoroalkyl groups having from 1 to about 30 carbon atoms and perfiuorochloroalkyl groups having from 1 to about 30 carbon atoms in which the carbon atom on to the C carbon atom in the formulais free from chlorine atoms directly attached thereto, and X is a halogen having an atomic number of less than 20, with mercuric sulfide.

3. The method claimed in claim 2 wherein the reaction is carried out in the presence of ionizing radiation.

4. The method claimed in claim 2 wherein the reaction is carried out under ultraviolet radiation.

5. A method for making compounds having the formula i h s Where R is a member of the class consisting of perfluoroalkyl groups having from 1 to about carbon atoms and perfluorochloroalkyl groups having from 1 to about 30 carbon atoms in which the carbon atom cc to the C carbon atom in the formula is free from chlorine atoms directly attached thereto, X is a halogen having an atomic number of less than 20 and n is from 2 to about 5, which comprises reacting a compound having the general formula RC XFI with mercuric sulfide.

6. The method claimed in claim 5 wherein R is a perfiuoroalkyl group.

7. The method claimed in claim 5 wherein R is a perfluorochloroalkyl group.

8. The method claimed in claim 5 wherein X is fluorine.

rine.

10. A method for making compounds of the formula where n is from 2 to about 5, which comprises reacting OF OF CF I with mercuric sulfide.

No references cited.

9. The method claimed in claim 5 wherein X is chlo- 

1. A METHOD FOR MAKING ORGANIC FLUORINE COMPOUNDS CONTANING SULFUR, WHICH COMPRISES REACTING AN IODIDE HAVING THE FORMULA 